Docker & JVM: A Perfect Match

Docker & JVM
A Perfect Match
Matthias Grüter // @mattgruter
Jfokus 2015

Your Toastmaster
Matthias Grüter

Containers
Credit: containersfirst.com.au

Shipping Containers
Credit: danielpivnick

Build, Ship and Run
Any App, Anywhere

Let's create some
containers!

Ports to the outside world
docker run p 9000:8080 ...
Format: [hostPort]:[containerPort]

Container Linking
1. Database container "redis1"
docker run name redis1 redis
2. Application container "myapp" (wants DB backend)
docker run link redis1:db myapp
Format: link [containerName]:[alias]

Docker Images
Container Blueprints
Source: homeinabox.blogspot.se

Example: Jenkins
FROM debian:jessie
# install java
RUN aptget update && aptget install y openjdk7jre
# install jenkins
ADD http://mirrors.jenkinsci.org/war/1.597/jenkins.war /
ENV JENKINS_HOME /jenkins
WORKDIR /jenkins
EXPOSE 8080
CMD ["java", "jar", "/jenkins.war"]

Example: Jenkins
Build:
docker build tag jenkins .
Run:
docker run p 8080:8080 jenkins

Data Volumes
Expose:
docker run v /data name db redis
Access:
docker run volumesfrom=db rsync r /data/ remote:/backup
Credit: Tony Cole

Docker and the JVM

Encapsulation (app + libs)
Memory management
Portability

Encapsulation (runtime)
Isolation & Containment
Portability

Docker and the JVM

Encapsulation
Sandboxing
Portability

Ecosystem
Docker API
Build system
Build/CI servers
Build repositories
...

Webapp
Gradle
plugins {
id 'application'
}
mainClassName = 'se.qubit.webapp.Main'
group = 'mattgruter'
repositories { jcenter() }
dependencies { ... }

Webapp
Gradle & Docker
plugins {
  id 'application'
  id 'se.transmode.docker' version '1.3'
}
mainClassName = 'se.qubit.webapp.Main'
group = 'mattgruter'
repositories { jcenter() }
dependencies { ... }
distDocker.dockerfile {
  EXPOSE 8080
}

Build
gradle distDocker
:‐)

Deploy
Wallet (Redis)
docker run d name db redis
Miner
docker run d link db:db mattgruter/qubitminer
Webapp
docker run link db:db p 8080:8080 mattgruter/qubitwebapp

Faster!
...

Your container is
NOT a VM
Stop treating it like one!

Corollary #1
Say no to sshd
use volumes, volumes, volumes
... and docker exec

Corollary #2
There can be only
one PID
Credit: imaginarywars.wordpress.com

Docker is a polyglot
tool!
So sorry, JVM!

Docker Hub
Automated Builds

Be Specific
Images are cheap, therefore ...
... build many small specific images.

Size Matters
Use small baseimages

Corollary
(e.g. apt‐get clean, multi‐line run)

Use the cache, Luke!
Move ADD & COPY to end of Dockerfile
(they invalidate the cache)

What does the future hold?
Credit: www.clipartbest.com/8balllogo

Docker & JVM: A Perfect Match

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